Formation of solid phase epitaxial GeSn and its application to high-performance N-MOSFETs and low-resistivity contact

Single crystalline GeSn grown on Ge substrate by solid phase epitaxy was developed and employed as the platform to implement Al
₂
O
₃
-gated N-MOSFETs. O
₂
plasma treatment was confirmed to be an effective avenue for surface passivation by forming GeSnOx. The passivation makes a D
_it
as low as 1.62×10
¹¹
cm
^-2
eV-1 and high peak mobility of 518 cm
²
/(Vs). To mitigate FL pinning on n-GeSn for low contact resistivity, O
₂
plasma treatment and formation of Yb stanogermanide on GeSn were respectively employed to suppress surface states. The significant FL depinning is evidenced by the Φ
_BN
of 0.12~0.13 eV with ρ
_c
less than 4.0×10
^-7
Ω-cm
²
. The promising processes gain an outlook on empowering high-performance GeSn devices.